Industrial products, in addition to providing desirable performance, also must improve appearance, touch feeling and identification of the product through innovative and aesthetic profile design to enhance product orientation and prices on the market. Many conventional industrial products, such as handsets or notebook computers, have plastic casings. Although some of them are coated with paint to provide shades different from plastics, they still have notable plastic touch feeling. After being used for a period of time or being subjected to abrasion, the paint on the surface is worn away and the plastic surface is exposed. Hence the plastic casing coated with paint generally does not have attractive appearance and desirable touch feeling.
To remedy the aforesaid shortcomings, In-Mold decoration (IMD) technique has been developed. IMD technique has gone through a lot of progress and now can be divided into many types of processes such as IMR (In-Mold Roller), IMF (In-Mold Forming), etc. Its core concept includes placing a decorative film printed with designed colors and patterns in an injection mold, then plastic material is directly injected onto the decorative film to couple the plastic material and decorative film together to form a finished product. A reference can be found in R.O.C. publication No. 200819272 entitled “In-Mold decoration printing method”. It discloses that a patterned film is pre-disposed on the inner wall of a mold. The mold has a pouring opening to inject plastic material into a mold cavity to couple with the patterned film. To avert creases from forming on the patterned film during injection of the plastic material, the mold has a plurality of air inlets communicating with the mold cavity to introduce airflow inside so that the plastic material is squeezed on the patterned film by the airflow, and the patterned film is smoothly and flatly attached to the inner wall of the mold. The aforesaid reference adopts IMD technique by injecting plastic material onto the film which provides diversified patterns and colors on outer surface of the film.
With constant developments of the IMD technique, its production speed and cost and product yield, appearance and physical strength have been greatly improved. However, the finished products formed by IMD provide merely alteration of the external appearance. Some electronic products need a further process by disposing electromagnetic isolation material on the finished products. This results in higher design and production costs. To further improve the IMD technique, other materials aside from attaching a decorative film on the finished product can be added to provide superior characteristics for the invention.